Antibiotic misuse, sometimes called antibiotic abuse or antibiotic overuse, refers to the misuse or overuse of antibiotics, with potentially serious effects on health. It is a contributing factor to the development of antibiotic resistance, including the creation of multidrug-resistant bacteria, informally called "super bugs": relatively harmless bacteria (such as staphylococcus, enterococcus and acinetobacter) can develop resistance to multiple antibiotics and cause life-threatening infections.

A quinolone antibiotic is any member of a large group of broad-spectrum bactericides that share a bicyclic core structure related to the compound 4-quinolone. They are used in human and veterinary medicine to treat bacterial infections, as well as in animal husbandry.

Nearly all quinolone antibiotics in modern use are fluoroquinolones, which contain a fluorine atom in their chemical structure and are effective against both Gram-negative and Gram-positive bacteria. One example is ciprofloxacin (Cipro), one of the most widely used antibiotics worldwide.

The Gonorrhea bacterium Neisseria gonorrhoeae has developed antibiotic resistance to many antibiotics.

The bacteria was first identified in 1879, although some Biblical scholars believe that references to the disease can be found as early as Parshat Metzora of the Old Testament.

In the 1940s effective treatment with penicillin became available, but by the 1970s resistant strains predominated. Resistance to penicillin has developed through two mechanisms: chromasomally mediated resistance (CMRNG) and penicillinase-mediated resistance (PPNG). CMRNG involves step wise mutation of penA, which codes for the penicillin-binding protein (PBP-2); mtr, which encodes an efflux pump that removes penicillin from the cell; and penB, which encodes the bacterial cell wall porins. PPNG involves the acquisition of a plasmid-borne beta-lactamase. "N. gonorrheoea" has a high affinity for horizontal gene transfer, and as a result, the existence of any strain resistant to a given drug could spread easily across strains.

Fluoroquinolones were a useful next-line treatment until resistance was achieved through efflux pumps and mutations to the gyrA gene, which encodes DNA gyrase. Third-generation cephalosporins have been used to treat gonorrhoea since 2007, but resistant strains have emerged. As of 2010, the recommended treatment is a single 250 mg intramuscular injection of ceftriaxone, sometimes in combination with azithromycin or doxycycline. However, certain strains of "N. gonorrhoeae" can be resistant to antibiotics usually that are normally used to treat it. These include: cefixime (an oral cephalosporin), ceftriaxone (an injectable cephalosporin), azithromycin, aminoglycosides, and tetracycline.

Fluoroquinolones are often used for genitourinary infections and are widely used in the treatment of hospital-acquired infections associated with urinary catheters. In community-acquired infections, they are recommended only when risk factors for multidrug resistance are present or after other antibiotic regimens have failed. However, for serious acute cases of pyelonephritis or bacterial prostatitis where the patient may need to be hospitalised, fluoroquinolones are recommended as first-line therapy.

Due to sickle-cell disease patients' being at increased risk for developing osteomyelitis from the "Salmonella "genus, fluoroquinolones are the "drugs of choice" due to their ability to enter bone tissue without chelating it, as tetracyclines are known to do.

Fluoroquinolones are featured prominently in guidelines for the treatment of hospital-acquired pneumonia.

Infection with "Y. enterocolitica" can cause a variety of symptoms depending on the age of the person infected, therefore it's often referred to as "monkey of diseases". Common symptoms in children are fever, abdominal pain, and diarrhea, which is often bloody. Symptoms typically develop 4 to 7 days after exposure and may last 1 to 3 weeks or longer. In older children and adults, right-sided abdominal pain and fever may be the predominant symptoms, and may be confused with appendicitis. In a small proportion of cases, complications such as skin rash, joint pains, ileitis, erythema nodosum, and sometimes septicemia, acute arthritis or the spread of bacteria to the bloodstream (bacteremia) can occur.

The side effects of penicillin are bodily responses to penicillin and closely related antibiotics that do not relate directly to its effect on bacteria. A side effect is an effect that is not intended with normal dosaging. Some of these reactions are visible and some occur in the body's organs or blood. Penicillins are a widely-used group of medications that are effective for the treatment of a wide variety of bacterial infections in human adults and children as well as other species. Some side effects are predictable, of which some are common but not serious, some are uncommon and serious and others are rare. The route of administration of penicillin can have an effect on the development of side effects. An example of this is irritation and inflammation that develops at a peripheral infusion site when penicillin is administered intravenously. In addition, penicillin is available in different forms. There are different penicillin medications (penicillin G benzathine, penicillin G potassium, penicillin G procaine, and penicillin V) as well as a number of β-lactam antibiotics derived from penicillin (e.g. amoxicillin) generally also referred to as "penicillin".

Side effects may only last for a short time and then go away. Side effects can be relieved in some cases with non pharmacological treatment. Some side effects require treatment to correct potentially serious and sometimes fatal reactions to penicillin. Penicillin has not been found to cause birth defects.

Yersiniosis is an infectious disease caused by a bacterium of the genus "Yersinia". In the United States, most yersiniosis infections among humans are caused by "Yersinia enterocolitica". The infection by "Y. enterocolitica" is also known as pseudotuberculosis. Yersiniosis is mentioned as a specific zoonotic disease to prevent outbreaks in European Council Directive 92/117/EEC.

Infection with " Y . enterocolitica" occurs most often in young children. The infection is thought to be contracted through the consumption of undercooked meat products, unpasteurized milk, or water contaminated by the bacteria. It has been also sometimes associated with handling raw chitterlings.

Another bacterium of the same genus, "Yersinia pestis", is the cause of Plague.

Multi-drug-resistant tuberculosis (MDR-TB) is a form of tuberculosis (TB) infection caused by bacteria that are resistant to treatment with at least two of the most powerful first-line anti-TB medications (drugs), isoniazid and rifampin. Some forms of TB are also resistant to second-line medications, and are called extensively drug-resistant TB (XDR-TB).

Tuberculosis is caused by infection with the bacteria Mycobacterium tuberculosis. Almost one in four people in the world are infected with TB bacteria. Only when the bacteria become active do people become ill with TB. Bacteria become active as a result of anything that can reduce the person’s immunity, such as HIV, advancing age, diabetes or other immunocompromising illnesses. TB can usually be treated with a course of four standard, or first-line, anti-TB drugs (i.e., isoniazid, rifampin and any fluoroquinolone).

However, beginning with the first antibiotic treatment for TB in 1943, some strains of the TB bacteria developed resistance to the standard drugs through genetic changes (see mechanisms.) Currently the majority of multidrug-resistant cases of TB are due to one strain of TB bacteria called the Beijing lineage. This process accelerates if incorrect or inadequate treatments are used, leading to the development and spread of multidrug-resistant TB (MDR-TB). Incorrect or inadequate treatment may be due to use of the wrong medications, use of only one medication (standard treatment is at least two drugs), not taking medication consistently or for the full treatment period (treatment is required for several months). Treatment of MDR-TB requires second-line drugs (i.e., fluoroquinolones, aminoglycosides, and others), which in general are less effective, more toxic and much more expensive than first-line drugs. Treatment schedules for MDR-TB involving fluoroquinolones and aminoglycosides can run for 2 years, compared to the 6 months of first-line drug treatment, and cost over $100,000 USD.If these second-line drugs are prescribed or taken incorrectly, further resistance can develop leading to XDR-TB.

Resistant strains of TB are already present in the population, so MDR-TB can be directly transmitted from an infected person to an uninfected person. In this case a previously untreated person develops a new case of MDR-TB. This is known as primary MDR-TB, and is responsible for up to 75% of cases. Acquired MDR-TB develops when a person with a non-resistant strain of TB is treated inadequately, resulting in the development of antibiotic resistance in the TB bacteria infecting them. These people can in turn infect other people with MDR-TB.

MDR-TB caused an estimated 480,000 new TB cases and 250,000 deaths in 2015. MDR-TB accounts for 3.3% of all new TB cases worldwide. Resistant forms of TB bacteria, either MDR-TB or rifampin-resistant TB, cause 3.9% of new TB cases and 21% of previously treated TB cases. Globally, most MDR-TB cases occur in South America, Southern Africa, India, China, and the former Soviet Union.

Treatment of MDR-TB requires treatment with second-line drugs, usually four or more anti-TB drugs for a minimum of 6 months, and possibly extending for 18–24 months if rifampin resistance has been identified in the specific strain of TB with which the patient has been infected. Under ideal program conditions, MDR-TB cure rates can approach 70%.

Many people have indicated that they have a side effect related to an allergic reaction to penicillin. It has been proposed that as many as 90% of those claiming to have an allergy to penicillin are able to take it. Identifying an allergy to penicillin requires a hypersensitivity skin test which diagnoses IgE-mediated immune responses caused by penicillin. This test is typically performed by an allergist who uses a skin-prick and intradermal injection of penicilloyl-polylysine, a negative control (normal saline), and a positive control (histamine).

There is a common side effect that can develop when other medications are used. This is the development of cross sensitivities to other antibiotics. If someone has developed side effects when taking penicillin, these side effects may develop with a new medication even though the person has not taken the new medication before. Those medications that may cause a cross sensitivity reaction are: carbapenems, ampicillin, cefazolin, cephalosporins and cloxacillin.

New or progressive infiltrate on the chest X-ray with one of the following:

- Fever > 37.8 °C (100 °F)

- Purulent sputum

- Leukocytosis > 10,000 cells/μl

In an elderly person, the first sign of hospital-acquired pneumonia may be mental changes or confusion.

Other symptoms may include:

- A cough with greenish or pus-like phlegm (sputum)

- Fever and chills

- General discomfort, uneasiness, or ill feeling (malaise)

- Loss of appetite

- Nausea and vomiting

- Sharp chest pain that gets worse with deep breathing or coughing

- Shortness of breath

- Decreased blood pressure and fast heart rate

Common situations in which antibiotics are overused include the following:

- Apparent viral respiratory illness in children should not be treated with antibiotics. If there is a diagnosis of bacterial infection, then antibiotics may be used.

- When children with ear tubes get ear infections, they should have antibiotic eardrops put into their ears to go to the infection rather than having oral antibiotics which are more likely to have unwanted side effects.

- Swimmer's ear should be treated with antibiotic eardrops, not oral antibiotics.

- Sinusitis should not be treated with antibiotics because it is usually caused by a virus, and even when it is caused by a bacteria, antibiotics are not indicated except in atypical circumstances as it usually resolves without treatment.

- Viral conjunctivitis should not be treated with antibiotics. Antibiotics should only be used with confirmation that a patient has bacterial conjunctivitis.

- Older persons often have bacteria in their urine which is detected in routine urine tests, but unless the person has the symptoms of a urinary tract infection, antibiotics should not be used in response.

- Eczema should not be treated with oral antibiotics. Dry skin can be treated with lotions or other symptom treatments.

- The use of topical antibiotics to treat surgical wounds does not reduce infection rates in comparison with non-antibiotic ointment or no ointment at all.

Ventilator-associated pneumonia (VAP) is a sub-type of hospital-acquired pneumonia (HAP) which occurs in people who are receiving mechanical ventilation. VAP is not characterized by the causative agents; rather, as its name implies, definition of VAP is restricted to patients undergoing mechanical ventilation while in a hospital. A positive culture after intubation is indicative of ventilator-associated pneumonia and is diagnosed as such. In order to appropriately categorize the causative agent or mechanism it is usually recommended to obtain a culture prior to initiating mechanical ventilation as a reference.

Bacterial pneumonia is a type of pneumonia caused by bacterial infection.

"Streptococcus pneumoniae" () is the most common bacterial cause of pneumonia in all age groups except newborn infants. "Streptococcus pneumoniae" is a Gram-positive bacterium that often lives in the throat of people who do not have pneumonia.

Other important Gram-positive causes of pneumonia are "Staphylococcus aureus" () and "Bacillus anthracis".

Ceftriaxone and cefixime are third generation cephalosporins and are often used as treatments for "N. gonorrhoeae infections". The cephalosporins are part of a larger beta-lactam family of antibiotics. The newly discovered H041 strain of "N. gonorrhoeae", originally isolated from a commercial sex worker in Japan, was shown to be resistant to this antibiotic.

The possible mechanisms of resistance to this antibiotic are as follows:

1. an alteration of more than four amino acids in the C-terminal end of the PBP-2, which would result in the antibiotic being unable to bind to its target

2. mutations in the promoter regions of "mtr", resulting in the overexpression of genes that code for efflux pumps

3. mutations in the "penB" gene that encodes for the bacterial porin. This form of resistance has only been observed with ceftriaxone which is administered through an intramuscular injection.

Usually, multidrug-resistant tuberculosis can be cured with long treatments of second-line drugs, but these are more expensive than first-line drugs and have more adverse effects. The treatment and prognosis of MDR-TB are much more akin to those for cancer than to those for infection. MDR-TB has a mortality rate of up to 80%, which depends on a number of factors, including

1. How many drugs the organism is resistant to (the fewer the better)

2. How many drugs the patient is given (patients treated with five or more drugs do better)

3. Whether an injectable drug is given or not (it should be given for the first three months at least)

4. The expertise and experience of the physician responsible

5. How co-operative the patient is with treatment (treatment is arduous and long, and requires persistence and determination on the part of the patient)

6. Whether the patient is HIV positive or not (HIV co-infection is associated with an increased mortality).

The majority of patients suffering from multi-drug-resistant tuberculosis do not receive treatment, as they are found in underdeveloped countries or in poverty. Denial of treatment remains a difficult human rights issue, as the high cost of second-line medications often precludes those who cannot afford therapy.

A study of cost-effective strategies for tuberculosis control supported three major policies. First, the treatment of smear-positive cases in DOTS programs must be the foundation of any tuberculosis control approach, and should be a basic practice for all control programs. Second, there is a powerful economic case for treating smear-negative and extra-pulmonary cases in DOTS programs along with treating smear-negative and extra-pulmonary cases in DOTS programs as a new WHO “STOP TB” approach and the second global plan for tuberculosis control. Last, but not least, the study shows that significant scaling up of all interventions is needed in the next 10 years if the millennium development goal and related goals for tuberculosis control are to be achieved. If the case detection rate can be improved, this will guarantee that people who gain access to treatment facilities are covered and that coverage is widely distributed to people who do not now have access.

In general, treatment courses are measured in months to years; MDR-TB may require surgery, and death rates remain high despite optimal treatment. However, good outcomes for patients are still possible.

The treatment of MDR-TB must be undertaken by physicians experienced in the treatment of MDR-TB. Mortality and morbidity in patients treated in non-specialist centers are significantly higher to those of patients treated in specialist centers. Treatment of MDR-TB must be done on the basis of sensitivity testing: it is impossible to treat such patients without this information. When treating a patient with suspected MDR-TB, pending the result of laboratory sensitivity testing, the patient could be started on SHREZ (Streptomycin+ isonicotinyl Hydrazine+ Rifampicin+Ethambutol+ pyraZinamide) and moxifloxacin with cycloserine. There is evidence that previous therapy with a drug for more than a month is associated with diminished efficacy of that drug regardless of "in vitro" tests indicating susceptibility. Hence, a detailed knowledge of the treatment history of each patient is essential. In addition to the obvious risks (i.e., known exposure to a patient with MDR-TB), risk factors for MDR-TB include HIV infection, previous incarceration, failed TB treatment, failure to respond to standard TB treatment, and relapse following standard TB treatment.

A gene probe for "rpoB" is available in some countries. This serves as a useful marker for MDR-TB, because isolated RMP resistance is rare (except when patients have a history of being treated with rifampicin alone). If the results of a gene probe ("rpoB") are known to be positive, then it is reasonable to omit RMP and to use SHEZ+MXF+cycloserine. The reason for maintaining the patient on INH is that INH is so potent in treating TB that it is foolish to omit it until there is microbiological proof that it is ineffective (even though isoniazid resistance so commonly occurs with rifampicin resistance).

When sensitivities are known and the isolate is confirmed as resistant to both INH and RMP, five drugs should be chosen in the following order (based on known sensitivities):

- an aminoglycoside (e.g., amikacin, kanamycin) or polypeptide antibiotic (e.g., capreomycin)

- pyrazinamide

- ethambutol

- a fluoroquinolone (e.g., moxifloxacin (ciprofloxacin) should no longer be used);

- rifabutin

- cycloserine

- a thioamide: prothionamide or ethionamide

- PAS

- a macrolide: e.g., clarithromycin

- linezolid

- high-dose INH (if low-level resistance)

- interferon-γ

- thioridazine

- Ampicillin

"Note:" Drugs placed nearer the top of the list are more effective and less toxic; drugs placed nearer the bottom of the list are less effective or more toxic, or more difficult to obtain.

In general, resistance to one drug within a class means resistance to all drugs within that class, but a notable exception is rifabutin: Rifampicin-resistance does not always mean rifabutin-resistance, and the laboratory should be asked to test for it. It is possible to use only one drug within each drug class. If it is difficult finding five drugs to treat then the clinician can request that high-level INH-resistance be looked for. If the strain has only low-level INH-resistance (resistance at 0.2 mg/l INH, but sensitive at 1.0 mg/l INH), then high dose INH can be used as part of the regimen. When counting drugs, PZA and interferon count as zero; that is to say, when adding PZA to a four-drug regimen, another drug must be chosen to make five. It is not possible to use more than one injectable (STM, capreomycin or amikacin), because the toxic effect of these drugs is additive: If possible, the aminoglycoside should be given daily for a minimum of three months (and perhaps thrice weekly thereafter). Ciprofloxacin should not be used in the treatment of tuberculosis if other fluoroquinolones are available.

There is no intermittent regimen validated for use in MDR-TB, but clinical experience is that giving injectable drugs for five days a week (because there is no-one available to give the drug at weekends) does not seem to result in inferior results. Directly observed therapy helps to improve outcomes in MDR-TB and should be considered an integral part of the treatment of MDR-TB.

Response to treatment must be obtained by repeated sputum cultures (monthly if possible). Treatment for MDR-TB must be given for a minimum of 18 months and cannot be stopped until the patient has been culture-negative for a minimum of nine months. It is not unusual for patients with MDR-TB to be on treatment for two years or more.

Patients with MDR-TB should be isolated in negative-pressure rooms, if possible. Patients with MDR-TB should not be accommodated on the same ward as immunosuppressed patients (HIV-infected patients, or patients on immunosuppressive drugs). Careful monitoring of compliance with treatment is crucial to the management of MDR-TB (and some physicians insist on hospitalisation if only for this reason). Some physicians will insist that these patients remain isolated until their sputum is smear-negative, or even culture-negative (which may take many months, or even years). Keeping these patients in hospital for weeks (or months) on end may be a practical or physical impossibility, and the final decision depends on the clinical judgement of the physician treating that patient. The attending physician should make full use of therapeutic drug monitoring (in particular, of the aminoglycosides) both to monitor compliance and to avoid toxic effects.

Some supplements may be useful as adjuncts in the treatment of tuberculosis, but, for the purposes of counting drugs for MDR-TB, they count as zero (if four drugs are already in the regimen, it may be beneficial to add arginine or vitamin D or both, but another drug will be needed to make five).

- arginine (peanuts are a good source)

- vitamin D

- Dzherelo

- V5 Immunitor

The drugs listed below have been used in desperation, and it is uncertain as to whether they are effective at all. They are used when it is not possible to find five drugs from the list above.

- imipenem

- co-amoxiclav

- clofazimine

- prochlorperazine

- metronidazole

On December 28, 2012 the U.S. Food and Drug Administration (FDA) approved bedaquiline (marketed as Sirturo by Johnson & Johnson) to treat multi-drug resistant tuberculosis, the first new treatment in 40 years. Sirturo is to be used in a combination therapy for patients who have failed standard treatment and have no other options. Sirturo is an adenosine triphosphate synthase (ATP synthase) inhibitor.

The following drugs are experimental compounds that are not commercially available, but may be obtained from the manufacturer as part of a clinical trial or on a compassionate basis. Their efficacy and safety are unknown:

- pretomanid (manufactured by Novartis, developed in partnership with TB Alliance)

- delamanid

In cases of extremely resistant disease, surgery to remove infection portions of the lung is, in general, the final option. The center with the largest experience in this is the National Jewish Medical and Research Center in Denver, Colorado. In 17 years of experience, they have performed 180 operations; of these, 98 were lobectomies and 82 were pneumonectomies. There is a 3.3% operative mortality, with an additional 6.8% dying following the operation; 12% experienced significant morbidity (in particular, extreme breathlessness). Of 91 patients who were culture-positive before surgery, only 4 were culture-positive after surgery.

The resurgence of tuberculosis in the United States, the advent of HIV-related tuberculosis, and the development of strains of TB resistant to the first-line therapies developed in recent decades—serve to reinforce the thesis that Mycobacterium tuberculosis, the causative organism, makes its own preferential option for the poor. The simple truth is that almost all tuberculosis deaths result from a lack of access to existing effective therapy.

It is also called the eruptive phase or tissue phase, in which the patients develop a cutaneous rash produced by a proliferation of endothelial cells and is known as "Peruvian warts" or "verruga peruana". Depending on the size and characteristics of the lesions, there are three types: miliary (1–4 mm), nodular or subdermic, and mular (>5mm). Miliary lesions are the most common. The lesions often ulcerate and bleed.

The most common findings are bleeding of verrugas, fever, malaise, arthralgias (joint pain), anorexia, myalgias, pallor, lymphadenopathy, and liver and spleen enlargement.

On microscopic examination, the chronic phase and its rash are produced by angioblastic hyperplasia, or the increased rates and volume of cell growth in the tissues that form blood vessels. This results in a loss of contact between cells and a loss of normal functioning.

The chronic phase is the more common phase. Mortality during the chronic phase is very low.

It is also called the hematic phase. The most common findings are fever (usually sustained, but with temperature no greater than 102 °F (39 °C)), pale appearance, malaise, painless liver enlargement, jaundice, enlarged lymph nodes, and enlarged spleen. This phase is characterized by severe hemolytic anemia and transient immunosuppression. The case fatality ratios of untreated patients exceeded 40% but reach around 90% when opportunistic infection with "Salmonella spp" occurs. In a recent study, the attack rate was 13.8% (123 cases) and the case-fatality rate was 0.7%.

Other symptoms include a headache, muscle aches, and general abdominal pain. Some studies have suggested a link between Carrion's disease and heart murmurs due to the disease's impact on the circulatory system. In children, symptoms of anorexia, nausea, and vomiting have been investigated as possible symptoms of the disease.

Most of the mortality of Carrion's disease occurs during the acute phase. Studies vary in their estimates of mortality. In one study, mortality has been estimated as low as just 1% in studies of hospitalized patients, to as high as 88% in untreated, unhospitalized patients. In developed countries, where the disease rarely occurs, it is recommended to seek the advice of a specialist in infectious disease when diagnosed. Mortality is often thought to be due to subsequent infections due to the weakened immune symptoms and opportunistic pathogen invasion, or consequences of malnutrition due to weight loss in children. In a study focusing on pediatric and gestational effects of the disease, mortality rates for pregnant women with the acute phase were been estimated at 40% and rates of spontaneous abortion in another 40%.

The proximity of the brain to the sinuses makes the most dangerous complication of sinusitis, particularly involving the frontal and sphenoid sinuses, infection of the brain by the invasion of anaerobic bacteria through the bones or blood vessels. Abscesses, meningitis and other life-threatening conditions may result. In extreme cases the patient may experience mild personality changes, headache, altered consciousness, visual problems, seizures, coma and possibly death.

Sinus infection can spread through anastomosing veins or by direct extension to close structures. Orbital complications were categorized by Chandler et al. into five stages according to their severity (see table). Contiguous spread to the orbit may result in periorbital cellulitis, subperiosteal abscess, orbital cellulitis, and abscess. Orbital cellulitis can complicate acute ethmoiditis if anterior and posterior ethmoidal veins thrombophlebitis enables the spread of the infection to the lateral or orbital side of the ethmoid labyrinth. Sinusitis may extend to the central nervous system, where it may cause cavernous sinus thrombosis, retrograde meningitis, and epidural, subdural, and brain abscesses. Orbital symptoms frequently precede intracranial spread of the infection . Other complications include sinobronchitis, maxillary osteomyelitis, and frontal bone osteomyelitis. Osteomyelitis of the frontal bone often originates from a spreading thrombo-phlebitis. A periostitis of the frontal sinus causes an osteitis and a periostitis of the outer membrane, which produces a tender, puffy swelling of the forehead.

The diagnosis of these complications can be assisted by noting local tenderness and dull pain, and can be confirmed by CT and nuclear isotope scanning. The most common microbial causes are anaerobic bacteria and "S. aureus". Treatment includes performing surgical drainage and administration of antimicrobial therapy. Surgical debridement is rarely required after an extended course of parenteral antimicrobial therapy. Antibiotics should be administered for at least 6 weeks. Continuous monitoring of patients for possible intracranial complication is advised.

Maxillary sinusitis may also be of dental origin ("odontogenic sinusitis"), and constitutes a significant percentage (about 20% of all cases of maxillary sinusitis), given the close proximity of the teeth and the sinus floor. The cause of this situation is usually a periapical or periodontal infection of a maxillary posterior tooth, where the inflammatory exudate has eroded through the bone superiorly to drain into the maxillary sinus. Once an odontogenic infection involves the maxillary sinus, it is possible that it may then spread to the orbit or to the ethmoid sinus. Complementary tests based on conventional radiology techniques and modern technology may be indicated, based on the clinical context.

Chronic sinusitis can also be caused indirectly through a common but slight abnormality in the auditory or eustachian tube, which is connected to the sinus cavities and the throat. This tube is usually almost level with the eye sockets but when this sometimes hereditary abnormality is present, it is below this level and sometimes level with the vestibule or nasal entrance.

A number of studies have demonstrated adverse reactions in pets after administering vaccines to both dogs and cats. Concern about adverse effects has led to revised guidelines that alter the recommended frequency and methods/locations for both vaccination of dogs and feline vaccination.

A little known and often misdiagnosed reaction to the rabies vaccine in dogs, this problem may develop near or over the vaccine administration site and around the vaccine material that was injected, or as a more widespread reaction. Symptoms include ulcers, scabs, darkening of the skin, lumps at the vaccine site, and scarring with loss of hair. In addition to the vaccination site, lesions most often develop on the ear flaps (pinnae), on the elbows and hocks, in the center of the footpads and on the face. Scarring may be permanent. Dogs do not usually seem ill, but may develop fever. Symptoms may show up within weeks of vaccination, or may take months to develop noticeably.

Dogs with active lesion development and / or widespread disease may be treated with pentoxyfylline, a drug that is useful in small vessel vasculitis, or tacrolimus, an ointment that will help suppress the inflammation in the affected areas.

Owners and veterinarians of dogs who have developed this type of reaction should review the vaccination protocol critically and try to reduce future vaccinations to the extent medically and legally possible. At the very least, vaccines from the same manufacturer should be avoided. It is also recommended that the location in which future vaccinations are administered should be changed to the rear leg, as far down on the leg as possible and should be given in the muscle rather than under the skin.

The primary skin lesion usually starts with a macule that is painless, round and erythematous. Then, it develops into a pustule, and then a bulla with central hemorrhagic focus. The bullae progresses into an ulcer which extends laterally. Finally it becomes a gangrenous ulcer with central black eschar surrounded by erythematous halo.

The lesion may be single or multiple. They are most commonly seen in perineum and under arm pit. However, it can occur in any part of the body.

Ecthyma gangrenosum is a type of skin lesion characterized by vesicles or blisters which rapidly evolve into pustules and necrotic ulcers with undermined tender erythematous border. "Ecthyma" means a pus forming infection of the skin with an ulcer, "gangrenosum" means the gangrene or necrosis. It is the pathognomonic of "Pseudomonas aeruginosa" bacteremia. "Pseudomonas aeruginosa" is a gram negative, aerobic, coccobacillus bacterium.

This type of skin lesion was first described in association with "Pseudomonas aeruginosa" by L. Barker in 1897. It was given the name "ecthyma gangrenosum" by Hitschmann and Kreibich.

It mostly occurs in patients with underlying immunocompromised conditions (e.g. Malignancy). Although most cases are found in "Pseudomonas aeruginosa" infection, there are recent reports of this skin lesion associated with other microorganisms, such as "Escherichia coli, Citrobacter freundii, Klebsiella pneumonia", various other Pseudomonas species, and "Morganella morganii."

Untreated, acute epididymitis's major complications are abscess formation and testicular infarction. Chronic epididymitis can lead to permanent damage or even destruction of the epididymis and testicle (resulting in infertility and/or hypogonadism), and infection may spread to any other organ or system of the body. Chronic pain is also an associated complication for untreated chronic epididymitis.